Gas regulating device for a firearm



J1me 1956 c. E. SIMPSON GAS REGULATING DEVICE FOR A FIREARM V EN TOR. 511m .5 EIIL f7 7'7'0RNEY5.

Filed Nov. 7, 1952 I IN V? H BlEllEILE-E E.

United states Patent 2,148,662 Patented June 5, 1956 lice GAS REGULATING DEVICE FORA ClarenceE. Simpson, Wilbraham', Mass., assignor to the United States of America as represented by the Secretary of the Army Application November 7, 1952, Serial No.319,445 2 Claims. (Cl. 8'9'19'3)' (Granted under Title 35, U. S. Code (1352), see. 266) The invent-ion described herein may be manufactured andused by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to gas-operated firearms and is more particularly directed to means for regulating the pressure of the actuating gases.

in gas-operated firearms, the pressure of the gases divetted from the barrel to the gas system must be sutficient to efficiently operate the cooperating mechanisms, yet should not be so excessive that the recoiling parts are actuated with undue violence and cause undesirable breakage of parts. Many conditions, however, vary the pressure of the gases received by the gas system and also the amount of force required to operate the firearm. For example, it is well known that the explosive force of ammunition varies, with consequent fluctuation of gas pressure. In addition, the gas port from the barrel to the gas cylinder through which the gases are diverted becomes carbonized, thereby reducing the size of the port and consequently the pressure of the gases. The atmospheric temperaturein which the firearm is operated is still another condition which affects the power of the gas system since a cold gas cylinder diminishes the pressure of the gases received therein, Then, too, the age of the firearm, as reflected in the efiiciency of the gas system and the facility of operation, affects the pressure requirements.

It isdesirable, therefore, that the size of the gas port leading from the barrel to the gas cylinder be regulable so that the pressure of the gases passing therethrough may be adjusted to compensate for the variations of the gas pressure produced by the above-mentioned conditions, and also for the varying power requirements of the cooperating mechanisms. Moreover, the regulating means should be easily adjusted in the field, and also easily removed to expose the gas ports for cleaning.

Accordingly, it is an object of this invention to provide a means for controlling the pressure of the gases diverted from the barrel to act on the gas piston in a gas-operated firearm.

It is a further object of this invention to provide a gas regulating device which is also the closure member for the end of the gas cylinder.

It is a specific object of this invention to provide a unitary gas regulating device and closure member for the gas cylinder of a firearm wherein the mounting means are not easily afiected by the carbonization produced during fire and, therefore, may be easily adjusted in the field or removed to clean the gas ports.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a fragmentary view of the front end of a firearm shown in longitudinal cross section;

Fig. 2 is a sectional view on the line 22 of Fig. 1; and

Fig. 3 is an exploded view of the gas regulating device.

In Fig. 1 there is shown a barrel 12 of a firearm, a tubular gas cylinder 13, and a bracket 14, integral with the forward end of gas cylinder 13, which encircles barrel 12 adjacent a gas port 15 therein. Provided in bracket 14 is a gas port 16 which aligns with gas port 15 of barrel 12.

As previously mentioned, gas cylinder 13 is hollow and slidably mounted therein is a piston 17 which cooperates with the operating mechanisms of the firearm. When piston 17 is in the forwardmost position, the forward face thereof lies to the rear of gas port 16. The forward portion of gas cylinder 13 is counterbored, as shown at 18,. and thereby forms a shoulder 19 forwardly of gas port 16.

Threadably mounted in counterbore 18 is the gas regulating device 28 of this invention. Regulating device 20' comprises a cylindrical regulator member 21 having a shaft 22 extending axially outward from one end, a mounting member 23 rotatably mounted on shaft 22, and an indexing member 24 secured to the end of shaft 22.

Regulator member 21 has a diameter substantially that of the bore of gas cylinder 13 and is insertable therein. Provided on regulator member 21, adjacent shaft 22, is an annular flange 28 of substantially the same diameter as counterbore 18. The junction of flange 28 with the outside periphery of regulator member 21 forms a shoulder 29.

The end of regulator member 21, opposite shaft 22, is hollowed to form a cavity portion 30. Provided radially around the circumference of regulator member 21 are a plurality of orifices, such as 34, 35 and 36 in Fig. 2, which communicate with cavity portion 3%. Orifices 34, 35 and 36 are of progressively larger diameters and are so arranged that when regulator member 21 is inserted in counterbore 18, and shoulder 29 thereon contacts shoulder 19 in gas cylinder 13, each orifice will fully communicate with gas port 16 when indexing member 24 is cor-' respondingly rotated.

Mounting member 23 is suitably threaded, as shown at 26, to permit engagement thereof with counterbore 18 and is provided with a hexagonal head 38. Mounting member 23 is also provided with an axial bore 39 for rotatably receiving shaft 22 of regulator member 21. Bore 3% is counterbored, as shown at 40, to form an annular shoulder 53.

Indexing member 24- is provided with a hub portion 41 axially mountable on the end of shaft 22, and a transverse pin 25 secures hub portion 41 thereto. A portion of hub 41 is insertable in counterbore 40 of mounting member 23 for a purpose to be explained later. Extending radially from that portion of hub -11 outside mounting member 23 is an arm 45 having a slightly greater length than the radius of mounting member 23. Arm 45 is terminated by an indexing arm 46 which extends at right angles thereto and is adjacent to and parallel with shaft 22. Indexing arm 46, which is of shorter length than shaft 22, is terminated by an upstanding lug 47.

Provided radially around the outer end of gas cylinder 13, are a series of rectangular slots, such as 50, 51 and 52 in Fig. 2, arranged to receive lug 47 of indexing member 24. The number of slots equal the number of orifices in regulator member 21 and they are radially positioned so that when regulator member 21 is rotated by indexing member 24 to align one of the orifices therein with gas port 16, lug 47 will be in alignment with a cooperating slot, which may be identified by such indicating means as a number impressed into bracket 14. For example, when orifice 34 is aligned with gas port 16, lug 47 is aligned with slot 51) and when orifice 35 is aligned with gas port 16, lug 4'7 is aligned with slot Si.

When assembling gas regulating device 2% into gas cylinder 13, indexing member 24 is first rotated to align lug 47 with the selected slot, shown as 51 in Fig. 2. Mounting member 23 is then threadably rotated into counterbore 18, moving regulator member 21 inwardly also until stopped by shoulder 29 thereon contacting shoulder 19 of gas cylinder 13. As regulator member 21 is moved inwardly, indexing member 24 secured thereto is drawn toward the forward face of bracket 14 until lug 47 thereon is securely seated in slot 51 when shoulders 19 and 29 contact. When shoulders 19 and 29 are in contact and lug 47 is securely seated in slot 51, orifice 35 is in full communication with gas port 16 and the gas system is ready for operation.

If more or less gas power is needed, mounting member 23 is unscrewed by means of hexagonal head 38 until lug 47 is free to rotate, but inasmuch as indexing arm 46 is shorter than shaft 22, mounting member 23 need not be unscrewed entirely out of engagement with gas cylinder 13. If less gas power is needed, indexing member 24 is then rotated to bring a smaller orifice, such as 34 in Fig. 2, into cooperation with gas port 16. If more gas power is required, a larger orifice, such as 36, is brought into communication with gas port 16.

Mounting member 23 is easily unscrewed from gas cylinder 13 as the hot gases received in gas cylinder 13 are prevented from reaching the threaded mounting portions to form therebetween adhesive and clogging deposits. This is achieved by the contact of shoulder 19 in gas cylinder 13 with shoulder 29 of regulator member 21 which thereby forms a gas seal to prevent the hot gases passing into gas cylinder 13 from reaching the threaded portions.

As mounting member 23 is unscrewed, shoulder 53 therein finally contacts the rearward face of hub portion 41 of. indexing member 24 to separate regulator member 21 from gas cylinder 13 in the event adhesive carbon deposits have been formed therebetween and thereby facilitate the removal and adjustment of gas regulator 21.

It is readily apparent that there is here provided a gas regulating device of simple, rugged construction which is easily regulated in the field and which may be easily removed to fully expose the gas ports and the interior of the gas cylinder for quick and convenient cleaning.

I claim:

1. A gas regulating device for a gas operated firearm having a barrel with a gas port leading therefrom, comprising in combination, a gas tube fixedly secured to the barrel and having a radially disposed gas port leading therefrom aligned with the gas port in the barrel, said gas tube having a hollow portion and being provided with a counterbore on the forward end thereof and having interior threads therein, said counterbore of said tube forming a shoulder in the rear end thereof juxtaposed to said hollow portion of said gas tube, a regulator rotatably mounted in said counterbore and positioned therein by an annular flange thereon seating against said shoulder in said counterbore, said regulator being provided with a head portion rearwardly of said flange arranged to rotatably seat in said hollow portion of said tube, a recess longitudinally disposed in the rear of said regulator with radially disposed orifices leading therefrom arranged for registry with said gas port in said tube, said regulator being provided with a reduced diametrical portion forwardly of said flange portion terminating in a reduced stem portion, a mounting member threadably mounted in said interior threads of said tube and bearing against said flange portion of said regulator whereby said flange is retained against said shoulder of said tube, said mounting member being provided with a longitudinally disposed bore and a counterbore forwardly thereof, said longitudinal bore of said mounting member constructed to receive the diametrical portion of said regulator, an indexing member fixedly secured on said stem portion and being provided with a hub portion rotatably mounted in said counterbore of said mounting member, said indexing member being provided with an upwardly extending arm on the front end thereof and having a rearwardly extending indexing lug, and said gas tube being provided with spaced apart radially disposed slots on the front end thereof for cooperation with said lug whereby the positioning of said indexing member in one of said slots aligns one of said orifices with said gas port of said gas tube.

2. In a gas operated firearm having a barrel, a gas tube fixedly secured to the barrel, and a gas passage between the tube and the barrel, the combination of a regulator having an enlarged cylindrical head portion at one end thereof rotatably insertable in the gas tube, said head portion having a cavity therein and a plurality of circumferentially disposed radial gas ports communicating with said cavity, an annular shoulder in the gas tube disposed forwardly of the gas passage therein, an annular flange on the exterior periphery of said head portion forwardly of said gas ports therein and engageable with said annular shoulder to position said regulator with said gas ports in the vertical plane of the gas passage in the gas tube, the front end of the gas tube having a threaded section terminating forwardly of said annular shoulder therein, a hollow locking member engageable in said threaded section of the gas tube and rotatable into contact with said head portion of said regulator to hold said annular flange thereon against said annular shoulder in the gas tube, a stem portion extending forwardly from said regulator head portion to project through said locking member, an indexing member fixedly secured to the projecting end of said stern portion, means associated with said indexing member for selectively aligning each of said gas ports in said head portion of said regulator with the gas passage in the gas tube, and means on said indexing member for transmitting the unlocking movement of said locking member to said regulator, said cavity in said regulator head portion and said annular flange thereon cooperating to prevent passage of discharge gases into contact with said threaded section in the gas tube and thereby eliminate the cause of deleterious carbon accumulation between the threads on said locking member and in the gas tube.

Zak Dec. 7, 1937 Moore Feb. 22, 1949 

